Variable imprint spacing apparatus for rotary printing machine



Nov. 4. 1969 E. L. RYSWICK VARIABLE IMPRINT SPACING APPARATUS FOR ROTARY PRINTING MACHINE 3 Sheets-Sheet 1 Filed Jan. 5, 1967 FIG-I INVENTOR. EDWJRD L- RYSWICK ATTORNEY VARIABLE IMPRINT SPAGING APPARATUS FOR ROTARY PRINTING MACHINE Nov. 4. 1969 QL Y K 3,476,046

Filed Jan. 5, 196? 3 Sheets-Sheet 2 In n IHI LI INVENTOR. EDWARD L' RYSWICK WWW ATTORNEY Nov. 4, 1969 E. L. RYSWICK VARIABLE IMPRINT SPACING APPARATUS FOR ROTARY PRINTING MACHINE 3 Sheets-Sheet 3 Filed Jan. 5, 1967 AUX INK DRIVE YFIG- a INVENTOR. EDWARD L' RYSWICK ATTORNEY was United States Patent US. Cl. 101-216 18 Claims ABSTRACT OF THE DISCLOSURE Variable imprint spacing is accomplished by a variable speed drive train for driving a rotary print cylinder faster or slower than the print stock, spring connection of the print cylinder to the drive train to allow the print cylinder to advance or retard and return to an unbiased normal position relative to the drive train, and a friction pad on the print cylinder to engage the impression cylinder during each imprint to synchronize the print cylinder with the print stock. An ink roll and its drive can be positioned at several stations around the periphery of the print cylinder for inking different numbers of print elements at imprint speed.

In prior art printing machines, different imprint intervals are accomplished by selecting a print cylinder having a circumference that is a multiple of the imprint interval desired. For example, for an imprint every six inches, print cylinders having circumferences of six inches, twelve inches, or eighteen inches, can be used, and one, two, or three print elements are secured on such print cylinders respectively. Since many size imprints and imprint spacings are demanded of the printing arts, any versatile rotary printing machine needs a multitude of print cylinders of diflerent circumferences. This requires a large investment in expensive equipment, creates storage and handling problems for a great number of print cylinders, and results in great expense and labor in selecting, changing, and adjusting print cylinders for each printing operation.

The objects of this invention include, without limitation:

(a) Eliminating the need for different size print cylinders in a rotary printing machine;

(b) Providing variable imprint spacing with a single sized print cylinder;

(0) Reducing the expense of changing a printing machine from one imprint interval to another;

(d) Reducing the total investment required for each rotary printing machine, and reducing storage, service, and maintenance expense for such machine;

(e) Reducing the cost and increasing the speed for setting up a printing machine for each printing operatron;

(f) Eliminating any smudging or other malfunction in a variable imprint interval rotary printing machine; and

(g) Providing a simpler, more economical, and more reliable variable speed drive for a variable imprint rotary printing machine.

These and other objects of the invention will be apparent hereinafter from the specification which describes the invention, its use, operation, and preferred embodiments, from the drawings which constitute a part of the disclosure, and from the subject matter claimed.

Generally, variable imprint spacing according to the invention is accomplished by a variable speed drive train for a print cylinder, a resilient takeup in such drive train to accommodate periodic speed changes of the print cylinder, and a friction pad drive angularly coextensive with print on the print cylinder for engaging an impression 3,476,046 Patented Nov. 4, 1969 cylinder to drive the print cylinder at the speed of the print stock during each imprint. The print element inking means is positionable at several stations for inking each print element at imprint speed.

In the drawings:

FIG. 1 shows a partially cutaway front elevation of a preferred embodiment of variable imprint spacing apparatus according to the invention;

FIG. 2 shows an elevation of the right side of the apparatus of FIG. 1;

FIG. 3 is a fragmentary section of a resilient takeup in the drive train of the inventive apparatus taken along the line 3--3 of FIG. 2;

FIG. 4 is an enlarged fragmentary section of the inventive apparatus taken along line 44 of FIG. 2;

FIG. 5 is a section view of the ink roll drive train for the inventive apparatus taken along the line 55 of FIG. 2;

FIG. 6 shows a side elevation of a movable ink pan and roll for the inventive apparatus;

FIG. 7 is a side elevation of an alternative resilient takeup for the print roll drive train of the inventive apparatus; and

FIG. 8 is a circuit diagram for an electric control for the preferred apparatus.

Throughout the drawings, corresponding parts are given the same reference numerals. The drawings illustrate a preferred embodiment of the inventive apparatus in the form of a rotary printing press for printing labels on continuous bag stock. Such a press is generally operated in cooperation with a bag-making machine (not shown). Although the invention has many other uses it will be described in relation to the illustrated printing press.

Referring especially to FIGS. 1 and 2, the illustrated press includes generally a rotary printing cylinder 11, a print element 12 fixed on the circumference of cylinder 11, and an impression cylinder 13 over which stock 14 is driven to receive imprints from print element 12. These elements are mounted between front frame 59 and rear frame 60 which are connected at various points by cross frame members 61. Ink mechanism 15 rolls ink onto print element 12 for transfer to stock 14 at impression cylinder 13. Print element 12 can be formed in a variety of known ways, and secured to print cylinder 11 in a known manner. Stock 14 is driven through machine 10 at a desired printing speed in the direction of the arrow. Stock 14 can be any web, tube, bag stock, or the like on which repeated imprint images are desired.

The moving elements of press 10 are powered from any convenient source through shaft 22 which is turned at the desired speed to set the stock and imprint speed for press 10. A gear 21 on shaft 22 meshed with a gear 20 on shaft 17 to drive shaft 17 in synchronization with shaft 22. Stock roll 18 is fixed to shaft 17, and from shaft 17, impression roll 13 and stock roll 19 are driven as best shown in FIGS. 2 and 5. Pulley 62 fixed to shaft 17 drives belt 63 and in turn pulleys 64 and 65 which are secured respectively to shafts 66 and 67 on which impression cylinder 13 and stock roll 19 are mounted respectively. Thus, both stock rolls 18 and 19 and impression roll 13 are all driven in synchronization to advance stock 14 at the desired imprint speed.

Printing of bag labels and other printing operations require imprints of different lengths and different spacing, so that a variety of image repeat intervals are required. In the past, variable imprint spacing has required changing the size of the print cylinder as described above, but a wide range of imprint spacings are obtainable with the single print cylinder 11 in the illustrated apparatus.

Print cylinder 11 is driven at an adjustable variable speed from shaft 22, and thus maintains a predetermined speed relationship with shaft 17 and stock 14. An adjustable conical pulley 23 is mounted on shaft 22 and drives belt 24 and fixed diameter pulley 25 on shaft 26. Another adjustable conical pulley 27 mounted on shaft 26 drives belt 28 to fixed diameter pulley 29 concentric with print cylinder 11. Shaft 26 is mounted on pivot arm 30 that is adjustably pivotal around pin 31 by means of bolt 32 and nut 33 to adjust the tension of the belts 24 and 28. Since pulleys 23 and 27 are adjustable to various diameters, pulley 29and shaft 34 can be driven at a variety of speeds relative to the speed of stock 14.

Pulley 29 is mounted on shaft 34 on which is fixed a driven arm 35 best illustrated in FIG. 4. The rotational motion of arm 35 is transmitted to print cylinder 11 through resilient takeup springs so that print cylinder 11 follows arm 35 through a resilient coupling.

A pair of generally semicircular tubes 36 and 37 are mounted on the end of print cylinder 11 to be concentric with the axis thereof. Each tube is formed with a slot extending along the length of its radially inward surface, and arm 35 can extend through such slots into the hollow interior of either tube. Each of the tubes 36 and 37 contains a respective coil spring 38 and 39 to be engaged and compressed by arm 35. The fixed ends of springs 38 and 39 are adjustably secured in place in tubes 36 and 37 by respective set screw abutment members 40 and 41 that extend through the slots in each respective tube and are tightened in place to adjust the tensions of springs 38 and 39. The movable ends of springs 38 and 39 rest against respective washers 42 and 43 which are retained within respective tubes 36 and 37 by abutments 44 and 45.

The head 46 of arm 35 normally rests between the ends of tubes 36 and 37. Neither spring 38 or 39 can bias head 46 beyond the respective terminal abutments 44 or 45 of tubes 36 and 37, so arm 35 normally rests in an unbiased equilibrium position between ends of tubes 36 and 37. The effect of a force deflecting print cylinder 11 relative to arm 35 is illustrated in FIG. 4. With arm 35 rotating in the direction of the arrow, FIG. 4 illustrates the effect of a retarding force on print cylinder 11 tending to slow down its rotation relative to arm 35. Head 46 of arm 35 engages washer 42 and compresses spring 38 as head 46 advances into tube 36.

When the force retarding print cylinder 11 relative to arm 35 is removed, spring 38 accelerates print cylinder 11 to force head 46 of arm 35 rotationally rearward out of tube 36. Washer 42 is stopped by abutment 44 when print cylinder 11 is advanced sufficiently far relative to arm 35, and at such point, spring 38 no longer biases arm 35. For forces rotationally advancing print cylinder 11 relative to arm 35, head 46 advances into tube 37 and compresses spring 39 for a similar opposite effect.

Thus, springs 38 and 39 absorb forces rotationally retarding or advancing print cylinder 11 relative to arm 35, and when such forces are removed, springs 38 and 39 return print cylinder 11 to its normal equilibrium position relative to arm 35. Through such resilient coupling print cylinder 11 can periodically accelerate and decelerate and return to its reference position relative to arm 35 as it rotates. Also, since the rotational speed of arm 35 is adjustable through pulleys 23 and 27, print cylinder 11 can move in a wide variety of speeds relative to stock 14.

FIG. 7 shows an alternative to springs 38 and 39. Helical springs 47 and 48 are secured to print cylinder 11 by means of adjustable tension screws 49 and 50 respectively. The free ends 51 and 52 of springs 47 and 48 extend into positions for engagement with head 46 of arm 35 to resist any rotational displacement of arm 35 relative to print cylinder 11. Stops 53 and 54 formed on print cylinder 11 behind arm 36 engage spring ends 51 and 52 to prevent their biasing head 46 at the relative positions illustrated. Any rotational displacement of print cylinder 11 relative to arm 35 forces head 46 against the spring end 51 or 52 to move such spring away from its respective stop 53 or 54. After the deflection force is removed, the deflected spring end returns to its respective stop, and arm 35 returns to its unbiased equilibrium position as illustrated.

To facilitate rotational acceleration and deceleration of print cylinder 11, it is preferably formed of light weight material and constructed to have as low a rotational inertia as possible. For such purposes, aluminum, fiberglass, and the like are preferred materials for print cylinder 11.

As best shown in FIG. 2, a pair of friction drive pads 55 and 56 are positioned at opposite ends of print element 12 on print cylinder 11. Pads 55 and 56 are disposed alongside print element 12 to engage impression cylinder 13 during each rotation of print cylinder 11 to synchronize the speed of print cylinder 11 with impression cylinder 13 for imprinting stock 14 in exact synchronization with its speed. For example, if print cylinder 11 is rotating at a peripheral speed that is faster than the speed of stock 14, friction pads 55 and 56, when they engage impression cylinder 13, slow down the print cylinder 11 to the exact speed of the stock so that the imprint from print element 12 is made in rolling synchronization with stock 14 without any slippage, smudging, or malfunction. After the imprint from print element 12 is completed, and the trailing edge of friction pads 55 and 56 pass beyond impression roll 13, the springs coupling print cylinder 11 to arm 35, advance print cylinder 11 rapidly to its normal reference position relative to arm 35. By such an arrangement, print cylinder 11 can be driven faster or slower than stock 14 for variable spacing of imprints, and yet is synchronized with stock 14 during each imprint.

Preferably, a pair of friction pads 55 and 56 are disposed axially adjacent each print element mounted on print cylinder 11. Pads 55 and 56 are sized to extend over at least the extent of arc of print cylinder 11 occupied by print element 12. Preferably, friction pads 55 and 56 rotationally precede print element 12 by an amount sufficient for engaging impression cylinder 13 before print element 12 engages stock 14, to take up any initial jarring or unevenness in the adjustment of speed of print cylinder 11 into synchronization with stock 14.

Friction pads 55 and 56 are preferably formed of rubber or similar material for engaging and gripping impression cylinder 13 smoothly and evenly during rotation of print cylinder 11. Also, friction pads 55 and 56 are spaced axially outward of the inking mechanism for inking print plate 12, so that no ink is deposited on friction pads 55 and 56. Furthermore, friction pads 55 and 56 are preferably spaced apart wider than stock 14, so that they synchronize print cylinder 11 with impression cylinder 13 and do not engage stock 14 directly.

It is known that a plurality of print elements can be mounted on a single imprint cylinder, and for such an arrangement a plurality of pads 55 and 56 are arranged alongside each print element for synchronizing print cylinder 11 with stock 14 for each imprint. By varying the number of print element on cylinder 11 and varying the speed of arm 35 by adjustment of pulleys 23 and 27, a wide variety of imprint spacings on stOCk 14 can be obtained. At least 20% differences in rotational speeds between print cylinder 11 and stock 14 can be brought into synchronization with the stock for imprinting by the spring takeup connection between arm 35 and print cylinder 11.

As illustrated in the drawings, a single print element 12 is mounted on print cylinder 11, and ink pan 15 with its ink roll 57 is positioned for inking a single print element. Since inking should be accomplished at the desired imprint speed to deposit the ink uniformly on the print element, friction pads 55 and 56 rotationally lead print element 12 by an angle sufiicient to engage impression cylinder 13 just before print element 12 engages ink roll This ynchronizes the speed for print cylinder 11 with stock 14 during the inking and imprint cycles,

Ink pan 15, with its ink roll 57, is movable according tothe invention, and can be positioned at several stations around the periphery of print cylinder 11. Ink pan 15 (best shown in FIG. 6) generally includes measuring roll 68 the lower periphery of which is immersed in ink, and ink roll 57 which engages and receives ink from measuring roll 68 and transfers it to print element 12. Measuring roll 68 is supported by arm 69 which is pivotal around pin 72 and is adjustable by screw 70 and nut 71 for its tension against ink roll 57. The tension or pressure between rolls 68 and 57 determines the amount of ink picked up by ink roll 57 and transferred to print element 12. End bearing cap 73 supports ink roll 57 in slot 74 formed in the wall of pan 15. Preferably, the slot-engaging surfaces of bearing cap 73 include 2 flat portions 95 arranged to be aligned with the side walls of slot 74 for easy removal of ink roll 57. The end walls 75 of pan 15 are cut away to expose a maximum amount of the periphery of ink roll 57, so that it can bear against print element 12 in several different orientations.

Pan 15 is arranged to be held in place at three different locations around print cylinder 11 for inking different numbers of print elements. Ink pan 15 as illustrated in FIG. 1 is positioned relative to print cylinder 11 for inking a single print element 12. Such position is chosen for arranging ink roll 7 as close to impression cylinder 13 as possible for both inking and imprinting quickly while print cylinder 11 is held to the speed of the stock. The illustrated position of ink pan 15 is designated by the letter A applied to the end of the shaft for ink roll 57. For two print elements arranged 180 apart on the periphery of print cylinder 11, ink pan 15 is moved to position the shaft of ink roll 57 in the position illustrated in phantom and identified by the letter B. In the B position, ink roll 57 inks one print element at the same time the other print element is printing, and since'friction pads adjacent each print element, drive print cylinder 11 in synchronization with the stock during each imprint, they also drive the opposite print element in synchronization with ink roll 57 during inking as is desired. For three print elements equally spaced around the periphery of print cylinder 11, ink pan 15 is moved to position the shaft of ink roll 57 in the phantom position identified by the letter C. Here again as a rotationally preceding print element is making an imprint so that print cylinder 11 is driven in synchronization with the stock during such imprint, a succeeding print element is driven in the same synchronization in engaging ink roll 57 for proper inking.

To facilitate easy movement of ink pan 15, between the A, B, and C positions described above, an ink pan holding frame is arranged at each of such positions. As best shown in FIG. 6, where one end of ink pan 15 and its holding frame are illustrated, the frame comprises a base 78, side plates 77, a pair of hook bars 79, and a pair of adjustable hook bar supports. Each hook'bar 79 is pivotable around pin 80, and has a lower support hook 81, and an upper hook 82. A clevis 83 engages and supports each hook bar 79 through pins 84, and clevises 83 are supported above 'base 78 by screws 85 that are adjustable by wing nuts 86. Springs 87 engage base 78 and clevises 83 to hold hook bars 79 as far above base 78 as allowed by adjustment of wing nuts 86. However, downward force on hook bars 79 can compress springs 87 to lower hook bars 79.

A pair of angled legs 76 at opposite ends of pan 15 rest on the upper surfaces of hook bars 79, and abut against lower hook portions 81 to fix the pan 15 in place. At the same time, upper hooks 82 engage corresponding recesses in forward wall 75 of pan 15 to fix pan 15 in place. Vertical adjustment of pan 15 and ink roll 57 is accomplished by wing nut 86. To move pan 15 from one location to another it is merely necessary to raise angle leg 76 off of hook bars 79, disengage upper hooks 82, and reseat the pan by a reverse operation at another holding station.

To facilitate easy movement of ink pan 15 from one location to another, ink pan drives are provided at each inking station. As best shown in FIGS. 2 and 5, a pulley 88 mounted on shaft 67, which is driven by belt 63 from pulley 62 on shaft 17, in turn drives belt 89 and pulleys 90, 91, and 92. Pulleys 90, 91, and 92 drive their respective shafts for powering the ink pan drive at respective A, B, and C locations. For example, as shown in FIG. 2, pulley 91 turns shaft 93 for driving ink pan 15 at inking stations C.

The gearing and drive mechanisms within ink pan 15 for driving measuring roll 68 and ink roll 57 are well known and not illustrated. Each of the ink drive shafts driven by pulleys 90, 91, and 92, such as shaft 93 illustrated in FIG. 2, is provided with a quick connection device 94 for rapid and easy coupling and uncoupling of the ink pan drive mechanism to the respective drive shafts.

It is preferred according to the invention, that when the illustrated press is stopped, no print element come to rest in engagement with stock 14 or ink roll 57. This insures that stock 14 is freely movable through the press, and more importantly, allows ink roll 57 to be driven independently of the main press drive, to prevent any drying of ink on ink roll 57. In the prior art, when a rotary press was stopped for a sufficient period of time, the complete ink pan with its rollers was moved away from the print cylinder and the ink rollers were driven at the removed location to prevent ink from drying rapidly on the ink rolls. However, according to the invention, ink roll 57 is out of engagement with print elements during a portion of each print cycle, and the press is stopped at one of these points so that the ink roll is free to keep running and prevent ink from drying on it without the ink pan being moved.

For such purposes, an auxiliary ink drive motor such as an electric motor 103 (FIG. 8) is provided for continuing the drive of ink roll 57 and measuring roll 68 through an overriding clutch (FIG. 5) selectively after press 10 is stopped. Furthermore, means are provided for stopping the press 10 in a proper position to make possible such driving of the ink roll 57.

Such a press control system is schematically illustrated in FIG. 8 and is intended to control press 10 when coupled to and driven through another apparatus such as a bagging machine. The inventive press control system can be adapted for independent press drive within the spirit of the invention.

The main drive motor for both the bagging machine (not shown) and the press is controlled by a relay 101. An auxiliary relay 102 is energized and deenergized at the same times as the main motor drive 100. Auxiliary ink drive 103 is an electric motor for driving the ink pan after the press has stopped, and ink drive 103 is selectively switched into operation by manual switch 104.

The condition of the circuit as illustrated in FIG. 8 shows the main motor drive 100 energized for driving both the bagging machine and the press, and in such position ,auxiliary relay 102 is energized, to hold open the circuit for auxiliary ink drive 103. At the same time relay 102. holds closed a circuit for magnetic clutch 105 which couples press 10 to the bagging machine. Clutch 105 preferably controls the connection of shaft 22 (FIG. 2) to adriven shaft on the bagging machine. Print switch 106 in the circuit for magnetic clutch 105 provides a parallel path for energizing magnetic clutch 105. Switch 106 is preferably a microswitch mounted near impression roll (as shown in FIG. 4) for engaging friction pads 55 or 56 on print cylinder 11. Switch 106 is thus closed whenever a friction pad engages impression cylinder 13, and at such times, a print element is engaging either stock 14 or ink roll 57, or both. Conversely, if switch 106 is open, no print element is engaging either stock 14 or ink roll 57.

If main drive motor 100 is shut off by opening of relay 101, relay 102 is deenergized to open the circuit to magnetic clutch 105 for disconnecting the press from its associated bagging machine. At the same time, the circuit is closed to auxiliary ink drive 103 which drives the ink pan drive train. If at this time, switch 106 is open, the press stops at once since no print element engages stock 14 or ink roll 57. The press thus stops in a proper condition so that the auxiliary ink drive 103 can drive the ink pan drive freely and keep the ink pan running. However, if switch 106 is closed when main drive 100 is deenergized, it provides a path for energizing magnetic clutch 105 in spite of the opening of relay 102, so that the press is not immediately disconnected from its associated bagging machine.

The moving parts of the bagging machine with which the press is coupled have greater inertia so the bagging machine comes to a stop more slowly. Hence, the bagging machine will continue to move to some extent after deenergization of main drive motor 100. If switch 106 is closed at the moment the main drive is shut off, indicating that a print element engages stock 14 or ink roll 57, magnetic clutch 105 remains energized, and the press moves along with the bagging machine to which it is coupled until switch 106 opens. When the press reaches a point at which switch 106 opens, magnetic clutch 105 is deenergized at once for uncoupling the press from its bagging machine and the press stops quickly in a proper position for allowing continued drive for its ink pan drive train.

Auxiliary ink drive 103 is preferably coupled to the shaft supporting pulley 92 as illustrated in FIGS. 2 and 5. The other pulleys 88, 90, and 91 in the ink pan drive train, are provided with overriding clutches 107 to allow continued drive of the ink pan drive shafts even though the main drive for the press is stopped.

Another advantageous feature offered by the inventive press is illustrated in FIG. 1. Impression cylinder 13 is supported by a spring loaded bearing support for adjustable engagement with print elements on print cylinder 11, and for moving back to allow passage of a jam or obstacle through the press. Previously, print cylinders were spring loaded to retreat from impression cylinders if jams of stock or other object passed between the print cylinder and the impression cylinder to prevent breaking of the printing machine. This was expedient because the print cylinders were removable, but it added considerably to the complications of a press. In the inventive press, a considerable saving can be effected by spring loading impression cylinder 13 for drawing back from print cylinder 11 to prevent damage from jams in the press.

To effect this, each end of impression cylinder 13 is supported in a slidable bearing block 108. Top and bottom slide rails 109 secured to the press frames 59 and 60, retain bearing blocks 108 in place for sliding motion. A pair of springs 110 are housed in bores in each bearing block 108, and extend from the rearward edge of bearing block 108 into engagement with the rearward edges of apertures 111 cut in frame 59 and 60 to support bearing blocks 108. Springs 110 push bearing blocks 108 forward as far as possible to bias impression cylinder 13 toward print cylinder 11. A screw 112 is threaded into the rearward edge of each bearing block 108 and is freely slidable in a bore 113 formed in frames 59 and 60. A nut 114 threaded on each screw 112 adjusts the amount of forward motion permitted by screw 112. Thus screw 112 and nut 114 limit the forward motion of impression cylinder 13 to adjust the pressure between stock 14 and a print element, and springs 110 allow rearward motion of impression cylinder 13 to pass any jams or obstacles between impression cylinder 13 and print cylinder 11.

Although the invention has been described relative to the illustrated printing press, it will be clear to those skilled in the art, that the invention is equally applicable to many forms of printing presses. A variety of drive trains, resilient couplings, detachable couplings, ink pan supports and drives, clutches and control circuits are well known and obviously available to those skilled in the art within the spirit of the invention.

Other features, advantages, and other specific embodiments of this invention will be apparent to those exercising ordinary skill in the pertinent art after considering the foregoing disclosure. In this regard, while a specific preferred embodiment has been described in detail, such disclosure is intended as illustrative rather than limiting, and other embodiments, variations, and modifications can be effected within the spirit and scope of the invention as disclosed and claimed. Furthermore, the following claimed subject matter is intended to cover fully all the aspects of the disclosed invention that are unobvious over prior art, including all equivalent embodiments.

I claim:

1. In a printing machine having a rotary print cylinder, a print element carried by said print cylinder and extending over a portion of the circumference of said print cylinder, means for driving stock past said print cylinder at a given speed, and means driven at said given speed including an ink roll for inking print element and an impression cylinder supporting said stock against said impression cylinder, improved means for variably spacing said imprints on said stock, said spacing means comprismg:

(a) a drive train having a member driven in rotation;

(b) means for adjusting said drive train to vary the speed of rotation of said driven member relative to said given speed;

(c) resilient means for connecting said print cylinder to said driven member, said resilient means being arranged to permit angular displacement of said print cylinder from a normally assumed equilibrium position relative to said driven member, and said resilient means being arranged to urge said print cylinder from any displaced position to said normally assumed equilibrium position;

((1) a friction pad axially adjacent said print element on said print cylinder and angularly coextensive with said print element, said pad extending radially to at least the radius of said print element, and said pad being arranged to engage an element of said means driven at said given speed to drive said print cylinder synchronously with said stock at said given speed during each of said imprints; and

(c) said ink roll being angularly spaced from said impression cylinder and arranged relative said friction pad so that engagement of said print element and said ink roll occurs only during said synchronous driving of said impression cylinder at said given speed.

2. The printing machine of claim 1 including means for limiting travel of said resilient means relative to said print cylinder when driven member is in said equilibrium position so that said driven member is not biased by said resilient means in said equilibrium position.

3. The printing machine of claim 2 wherein said driven member comprises a rotatable arm and said resilient means comprises a pair of springs mounted on said print cylinder and disposed on opposite sides of said arm to resist respective opposite rotational displacements of said arm relative to said print cylinder, and said limit means is arranged to limit travel of each of said springs toward said arm when said arm is in said equilibrium position.

4. The printing machine of claim 3 wherein said springs comprise a pair of flat spiral springs the free ends of which are disposed on opposite sides of said arm, and said limit means comprises a pair of abutments arranged on said print cylinder adjacent said arm.

5. The printing machine of claim 4 wherein the fixed ends of said springs are anchored to an adjustment screw for adjusting the tension of said springs.

6. The printing machine of claim 3 wherein each of said springs comprises a coil spring, a pair of curved and longitudinally slotted tubes are arranged on said print cylinder for housing said springs and for receiving the end of said arm for movement in said tubes, and said limit means comprises abutments at the ends of each of said tubes for stopping movement of each of said springs at said ends of said tubes so that said arm can rest in said equilibrium position between said ends of said tubes.

7. The printing machine of claim 6 wherein the ends of each of said springs opposite said abutment ends of said tubes are engaged by stop means that are positionable within said tubes to adjust the tension of each of said springs.

8. The printing machine of claim 7 including a pair of said friction pads adjacent opposite axial ends of said print element, said pads being spaced apart a distance greater than the width of said stock, means on said print cylinder for mounting a plurality of said print elements and corresponding friction pads, means for positioning said ink roll at different stations around the periphery of said print cylinder, means for driving said ink roll at said given speed at each of said stations, means for preventing the stopping of said print cylinder with said print element in engagement with said ink roll, means for driving said ink roll when said print cylinder is stopped to prevent drying of ink on said ink roll, and said print cylinder being formed of lightweight material for a low rotational inertia.

9. The printing machine of claim 8 including spring means for biasing said impression cylinder toward said print cylinder and wherein said friction pads extend angularly forward of said print element to bring said print cylinder to said given speed before said print element engages said stock.

10. The printing machine of claim 1 wherein said adjusting means for said drive train comprises adjustable conical pulleys.

11. The printing machine of claim 1 including a pair of said friction pads adjacent opposite axial ends of said print element, said pads being spaced apart a distance greater than the width of said stock.

12. The printing machine of claim 11 wherein said friction pads extend angularly forward of said print element to bring said print cylinder to said given speed before said print element engages said stock.

13. The printing machine of claim 1 wherein said print cylinder is formed of lightweight material for a low rotational inertia.

14. The printing machine of claim 1 including means on said print cylinder for mounting a plurality of said print elements and corresponding friction pads, and means for positioning said ink roll at different stations around the periphery of said print cylinder.

15. The printing machine of claim 14 including means for driving said ink roll at said given speed at each of said stations.

16. The printing machine of claim 15 including means for preventing the stopping of said print cylinder with said print element in engagement with said ink roll, and means for driving said ink roll when said print cylinder is stopped to prevent drying of ink on said ink roll.

17. The printing machine of claim 1 wherein said friction pad is arranged to engage said impression cylinder.

18. The printing machine of claim 1 including spring means for biasing said impression cylinder toward said print cylinder.

References Cited UNITED STATES PATENTS 2,603,153 7/1952 Warren et al 101219 2,743,671 5/1956 Weber et al 101-235 2,876,039 3/1959 Vogdt.

2,887,046 5/1959 Knops et al 101248 2,889,767 6/ 1959 Hirschey et al 10135 3,229,631 1/1966 Peterson 101-219 3,282,202 11/ 1966 Groth et al 101-350 XR FOREIGN PATENTS 1,068,100 10/1959 Germany.

868,168 5/ 1961 Great Britain.

ROBERT E. PULFREY, Primary Examiner I. REED FISHER, Assistant Examiner US. Cl. X.R. 101-350 

